Pacific Decadal Oscillation

Pacific Decadal Oscillation (PDO)

The Pacific decadal oscillation (PDO) is the leading pattern of decadal to multidecadal variability in North Pacific sea surface temperature (SST), excluding variability coherent with global average temperature changes. The PDO appears to be largely, though not entirely, the integrated response of the North Pacific Ocean SSTs to surface climate forcing by the El Niño–Southern Oscillation (ENSO) and from internal variability in the Aleutian low. The PDO is “ENSO-like” in the sense that the spatial structure of the PDO is well correlated with the spatial structure of ENSO variability over the North Pacific, though the PDO has noticeably more variability in the extratropical North Pacific and substantially less in the far eastern tropical Pacific.

ENSO-like SST variability on decadal and longer time scales extends to the South Pacific and to a small extent the Indian and Atlantic Oceans. This near-global pattern of variability is called the interdecadal Pacific oscillation (IPO). The spatial patterns of the PDO and IPO are similar in the North Pacific, and their time series are coherent on annual and longer time scales.